Source/WTF/wtf/MessageQueue.h - WebKit - Git at Google

 /*
  * Copyright (C) 2008, 2015-2016 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #pragma once

 #include <limits>
 #include <wtf/Assertions.h>
 #include <wtf/Condition.h>
 #include <wtf/Deque.h>
 #include <wtf/Lock.h>
 #include <wtf/MonotonicTime.h>
 #include <wtf/Noncopyable.h>

 namespace WTF {

     enum MessageQueueWaitResult {
         MessageQueueTerminated,       // Queue was destroyed while waiting for message.
         MessageQueueTimeout,          // Timeout was specified and it expired.
         MessageQueueMessageReceived   // A message was successfully received and returned.
     };

     // The queue takes ownership of messages and transfer it to the new owner
     // when messages are fetched from the queue.
     // Essentially, MessageQueue acts as a queue of std::unique_ptr<DataType>.
     template<typename DataType>
     class MessageQueue final {
         WTF_MAKE_FAST_ALLOCATED;
         WTF_MAKE_NONCOPYABLE(MessageQueue);
     public:
         MessageQueue() : m_killed(false) { }
         ~MessageQueue();

         void append(std::unique_ptr<DataType>);
         void appendAndKill(std::unique_ptr<DataType>);
         bool appendAndCheckEmpty(std::unique_ptr<DataType>);
         void prepend(std::unique_ptr<DataType>);

         std::unique_ptr<DataType> waitForMessage();
         std::unique_ptr<DataType> tryGetMessage();
         Deque<std::unique_ptr<DataType>> takeAllMessages();
         std::unique_ptr<DataType> tryGetMessageIgnoringKilled();
         template<typename Predicate>
         std::unique_ptr<DataType> waitForMessageFilteredWithTimeout(MessageQueueWaitResult&, Predicate&&, Seconds relativeTimeout);

         template<typename Predicate>
         void removeIf(Predicate&&);

         void kill();
         bool killed() const;

         // The result of isEmpty() is only valid if no other thread is manipulating the queue at the same time.
         bool isEmpty();

     private:
         mutable Lock m_lock;
         Condition m_condition;
         Deque<std::unique_ptr<DataType>> m_queue WTF_GUARDED_BY_LOCK(m_lock);
         bool m_killed WTF_GUARDED_BY_LOCK(m_lock);
     };

     template<typename DataType>
     MessageQueue<DataType>::~MessageQueue()
     {
     }

     template<typename DataType>
     inline void MessageQueue<DataType>::append(std::unique_ptr<DataType> message)
     {
         Locker lock { m_lock };
         m_queue.append(WTFMove(message));
         m_condition.notifyOne();
     }

     template<typename DataType>
     inline void MessageQueue<DataType>::appendAndKill(std::unique_ptr<DataType> message)
     {
         Locker lock { m_lock };
         m_queue.append(WTFMove(message));
         m_killed = true;
         m_condition.notifyAll();
     }

     // Returns true if the queue was empty before the item was added.
     template<typename DataType>
     inline bool MessageQueue<DataType>::appendAndCheckEmpty(std::unique_ptr<DataType> message)
     {
         Locker lock { m_lock };
         bool wasEmpty = m_queue.isEmpty();
         m_queue.append(WTFMove(message));
         m_condition.notifyOne();
         return wasEmpty;
     }

     template<typename DataType>
     inline void MessageQueue<DataType>::prepend(std::unique_ptr<DataType> message)
     {
         Locker lock { m_lock };
         m_queue.prepend(WTFMove(message));
         m_condition.notifyOne();
     }

     template<typename DataType>
     inline auto MessageQueue<DataType>::waitForMessage() -> std::unique_ptr<DataType>
     {
         MessageQueueWaitResult exitReason;
         std::unique_ptr<DataType> result = waitForMessageFilteredWithTimeout(exitReason, [](const DataType&) { return true; }, Seconds::infinity());
         ASSERT(exitReason == MessageQueueTerminated || exitReason == MessageQueueMessageReceived);
         return result;
     }

     template<typename DataType>
     template<typename Predicate>
     inline auto MessageQueue<DataType>::waitForMessageFilteredWithTimeout(MessageQueueWaitResult& result, Predicate&& predicate, Seconds relativeTimeout) -> std::unique_ptr<DataType>
     {
         Locker lock { m_lock };
         bool timedOut = false;

         MonotonicTime absoluteTimeout = MonotonicTime::now() + relativeTimeout;
         auto found = m_queue.end();
         while (!m_killed && !timedOut) {
             found = m_queue.findIf([&predicate](const std::unique_ptr<DataType>& ptr) -> bool {
                 ASSERT(ptr);
                 return predicate(*ptr);
             });
             if (found != m_queue.end())
                 break;

             timedOut = !m_condition.waitUntil(m_lock, absoluteTimeout);
         }

         ASSERT(!timedOut || absoluteTimeout != MonotonicTime::infinity());

         if (m_killed) {
             result = MessageQueueTerminated;
             return nullptr;
         }

         if (timedOut) {
             result = MessageQueueTimeout;
             return nullptr;
         }

         ASSERT(found != m_queue.end());
         std::unique_ptr<DataType> message = WTFMove(*found);
         m_queue.remove(found);
         result = MessageQueueMessageReceived;
         return message;
     }

     template<typename DataType>
     inline auto MessageQueue<DataType>::tryGetMessage() -> std::unique_ptr<DataType>
     {
         Locker lock { m_lock };
         if (m_killed)
             return nullptr;
         if (m_queue.isEmpty())
             return nullptr;

         return m_queue.takeFirst();
     }

     template<typename DataType>
     inline auto MessageQueue<DataType>::takeAllMessages() -> Deque<std::unique_ptr<DataType>>
     {
         Locker lock { m_lock };
         if (m_killed)
             return { };
         return WTFMove(m_queue);
     }

     template<typename DataType>
     inline auto MessageQueue<DataType>::tryGetMessageIgnoringKilled() -> std::unique_ptr<DataType>
     {
         Locker lock { m_lock };
         if (m_queue.isEmpty())
             return nullptr;

         return m_queue.takeFirst();
     }

     template<typename DataType>
     template<typename Predicate>
     inline void MessageQueue<DataType>::removeIf(Predicate&& predicate)
     {
         Locker lock { m_lock };
         while (true) {
             auto found = m_queue.findIf([&predicate](const std::unique_ptr<DataType>& ptr) -> bool {
                 ASSERT(ptr);
                 return predicate(*ptr);
             });

             if (found == m_queue.end())
                 break;

             m_queue.remove(found);
         }
     }

     template<typename DataType>
     inline bool MessageQueue<DataType>::isEmpty()
     {
         Locker lock { m_lock };
         if (m_killed)
             return true;
         return m_queue.isEmpty();
     }

     template<typename DataType>
     inline void MessageQueue<DataType>::kill()
     {
         Locker lock { m_lock };
         m_killed = true;
         m_condition.notifyAll();
     }

     template<typename DataType>
     inline bool MessageQueue<DataType>::killed() const
     {
         Locker lock { m_lock };
         return m_killed;
     }
 } // namespace WTF

 using WTF::MessageQueue;
 // MessageQueueWaitResult enum and all its values.
 using WTF::MessageQueueWaitResult;
 using WTF::MessageQueueTerminated;
 using WTF::MessageQueueTimeout;
 using WTF::MessageQueueMessageReceived;
	/*
	* Copyright (C) 2008, 2015-2016 Apple Inc. All rights reserved.
	* Copyright (C) 2009 Google Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the name of Apple Inc. ("Apple") nor the names of
	* its contributors may be used to endorse or promote products derived
	* from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#pragma once

	#include <limits>
	#include <wtf/Assertions.h>
	#include <wtf/Condition.h>
	#include <wtf/Deque.h>
	#include <wtf/Lock.h>
	#include <wtf/MonotonicTime.h>
	#include <wtf/Noncopyable.h>

	namespace WTF {

	enum MessageQueueWaitResult {
	MessageQueueTerminated, // Queue was destroyed while waiting for message.
	MessageQueueTimeout, // Timeout was specified and it expired.
	MessageQueueMessageReceived // A message was successfully received and returned.
	};

	// The queue takes ownership of messages and transfer it to the new owner
	// when messages are fetched from the queue.
	// Essentially, MessageQueue acts as a queue of std::unique_ptr<DataType>.
	template<typename DataType>
	class MessageQueue final {
	WTF_MAKE_FAST_ALLOCATED;
	WTF_MAKE_NONCOPYABLE(MessageQueue);
	public:
	MessageQueue() : m_killed(false) { }
	~MessageQueue();

	void append(std::unique_ptr<DataType>);
	void appendAndKill(std::unique_ptr<DataType>);
	bool appendAndCheckEmpty(std::unique_ptr<DataType>);
	void prepend(std::unique_ptr<DataType>);

	std::unique_ptr<DataType> waitForMessage();
	std::unique_ptr<DataType> tryGetMessage();
	Deque<std::unique_ptr<DataType>> takeAllMessages();
	std::unique_ptr<DataType> tryGetMessageIgnoringKilled();
	template<typename Predicate>
	std::unique_ptr<DataType> waitForMessageFilteredWithTimeout(MessageQueueWaitResult&, Predicate&&, Seconds relativeTimeout);

	template<typename Predicate>
	void removeIf(Predicate&&);

	void kill();
	bool killed() const;

	// The result of isEmpty() is only valid if no other thread is manipulating the queue at the same time.
	bool isEmpty();

	private:
	mutable Lock m_lock;
	Condition m_condition;
	Deque<std::unique_ptr<DataType>> m_queue WTF_GUARDED_BY_LOCK(m_lock);
	bool m_killed WTF_GUARDED_BY_LOCK(m_lock);
	};

	template<typename DataType>
	MessageQueue<DataType>::~MessageQueue()
	{
	}

	template<typename DataType>
	inline void MessageQueue<DataType>::append(std::unique_ptr<DataType> message)
	{
	Locker lock { m_lock };
	m_queue.append(WTFMove(message));
	m_condition.notifyOne();
	}

	template<typename DataType>
	inline void MessageQueue<DataType>::appendAndKill(std::unique_ptr<DataType> message)
	{
	Locker lock { m_lock };
	m_queue.append(WTFMove(message));
	m_killed = true;
	m_condition.notifyAll();
	}

	// Returns true if the queue was empty before the item was added.
	template<typename DataType>
	inline bool MessageQueue<DataType>::appendAndCheckEmpty(std::unique_ptr<DataType> message)
	{
	Locker lock { m_lock };
	bool wasEmpty = m_queue.isEmpty();
	m_queue.append(WTFMove(message));
	m_condition.notifyOne();
	return wasEmpty;
	}

	template<typename DataType>
	inline void MessageQueue<DataType>::prepend(std::unique_ptr<DataType> message)
	{
	Locker lock { m_lock };
	m_queue.prepend(WTFMove(message));
	m_condition.notifyOne();
	}

	template<typename DataType>
	inline auto MessageQueue<DataType>::waitForMessage() -> std::unique_ptr<DataType>
	{
	MessageQueueWaitResult exitReason;
	std::unique_ptr<DataType> result = waitForMessageFilteredWithTimeout(exitReason, [](const DataType&) { return true; }, Seconds::infinity());
	ASSERT(exitReason == MessageQueueTerminated \|\| exitReason == MessageQueueMessageReceived);
	return result;
	}

	template<typename DataType>
	template<typename Predicate>
	inline auto MessageQueue<DataType>::waitForMessageFilteredWithTimeout(MessageQueueWaitResult& result, Predicate&& predicate, Seconds relativeTimeout) -> std::unique_ptr<DataType>
	{
	Locker lock { m_lock };
	bool timedOut = false;

	MonotonicTime absoluteTimeout = MonotonicTime::now() + relativeTimeout;
	auto found = m_queue.end();
	while (!m_killed && !timedOut) {
	found = m_queue.findIf([&predicate](const std::unique_ptr<DataType>& ptr) -> bool {
	ASSERT(ptr);
	return predicate(*ptr);
	});
	if (found != m_queue.end())
	break;

	timedOut = !m_condition.waitUntil(m_lock, absoluteTimeout);
	}

	ASSERT(!timedOut \|\| absoluteTimeout != MonotonicTime::infinity());

	if (m_killed) {
	result = MessageQueueTerminated;
	return nullptr;
	}

	if (timedOut) {
	result = MessageQueueTimeout;
	return nullptr;
	}

	ASSERT(found != m_queue.end());
	std::unique_ptr<DataType> message = WTFMove(*found);
	m_queue.remove(found);
	result = MessageQueueMessageReceived;
	return message;
	}

	template<typename DataType>
	inline auto MessageQueue<DataType>::tryGetMessage() -> std::unique_ptr<DataType>
	{
	Locker lock { m_lock };
	if (m_killed)
	return nullptr;
	if (m_queue.isEmpty())
	return nullptr;

	return m_queue.takeFirst();
	}

	template<typename DataType>
	inline auto MessageQueue<DataType>::takeAllMessages() -> Deque<std::unique_ptr<DataType>>
	{
	Locker lock { m_lock };
	if (m_killed)
	return { };
	return WTFMove(m_queue);
	}

	template<typename DataType>
	inline auto MessageQueue<DataType>::tryGetMessageIgnoringKilled() -> std::unique_ptr<DataType>
	{
	Locker lock { m_lock };
	if (m_queue.isEmpty())
	return nullptr;

	return m_queue.takeFirst();
	}

	template<typename DataType>
	template<typename Predicate>
	inline void MessageQueue<DataType>::removeIf(Predicate&& predicate)
	{
	Locker lock { m_lock };
	while (true) {
	auto found = m_queue.findIf([&predicate](const std::unique_ptr<DataType>& ptr) -> bool {
	ASSERT(ptr);
	return predicate(*ptr);
	});

	if (found == m_queue.end())
	break;

	m_queue.remove(found);
	}
	}

	template<typename DataType>
	inline bool MessageQueue<DataType>::isEmpty()
	{
	Locker lock { m_lock };
	if (m_killed)
	return true;
	return m_queue.isEmpty();
	}

	template<typename DataType>
	inline void MessageQueue<DataType>::kill()
	{
	Locker lock { m_lock };
	m_killed = true;
	m_condition.notifyAll();
	}

	template<typename DataType>
	inline bool MessageQueue<DataType>::killed() const
	{
	Locker lock { m_lock };
	return m_killed;
	}
	} // namespace WTF

	using WTF::MessageQueue;
	// MessageQueueWaitResult enum and all its values.
	using WTF::MessageQueueWaitResult;
	using WTF::MessageQueueTerminated;
	using WTF::MessageQueueTimeout;
	using WTF::MessageQueueMessageReceived;